A)
For this tringle we can turn the figure like this:
now we have two right triangles and we can calulate the base of the first triangle with the sin law
the angle b is going to be:
Now the base is going to be:
and the base of the secon triangle is going to be:
And the area of the triangles is going to be:
so in total the area is going to be:
B)
the procedure is similar, first we turn the tiangle like this:
the angle a is going to be:
the angle b is going to be:
now the base is going to be:
and the base of the other triangle will be:
And the area of the triangles will be:
And the total area will be: